With the widespread use of electrical devices, the safety hazards caused by electrical devices are more and more concerned. In order to prevent electric shock accidents and reduce touch current, it is necessary to ground exposed conductive parts of the device that is floating, thus preventing electrical shock accidents through equipotential of a person and the device. Therefore, input for most of small and medium-sized power electrical devices is in a single-phase three-wire type, i.e., a live wire L, a neutral wire N and a grounding wire PE.
Grounding may provide a discharge loop for static electricity and other instantaneous energy, to ensure safe operation of the device. In some occasions, it may even cause a danger when the device is not connected to a grounding wire. For example, if a medical hydrogen generator is not connected to a ground, energy generated by the static electricity may produce electric spark due to lack of the discharge loop, which leads to explosion of the hydrogen, thus the electrical device is required to send an alarm signal or be directly cut off the operation when not grounded.
The reliable grounding of the electrical device may avoid the electric shock, which improves the safety of the electrical device and safety of the user. The existing electrical devices have a grounding wire, but there is no corresponding apparatus to judge whether or not the device is grounded when the device is operating. An existing grounding wire detection circuit is grounding wire missing detection of battery, to detect grounding between a battery shell and a cathode of the battery, which is not suitable for the grounding wire detection of devices using utility power grid. Therefore, the grounding wire detection of electrical devices using utility power grid is particularly important.
Therefore, a new grounding wire detection circuit, which may achieve real-time monitoring of whether or not a device is grounded, thus improving the safety of using the electrical device, is needed.
The above information disclosed in the Background section is only for enhancing the understanding of the background of the present disclosure, and therefore, it may include information that does not constitute prior art known to those skilled in the art.